Piper Jaffray comments on the DoJ investigation into Chinese firms, saying the probe likely puts smaller companies like Youku.com (YOKU-12%), Sky-mobi (MOBI-6.7%), and Dangdang (DANG-1.1%) at risk, given they do not have proven track records. The firm says SINA (SINA-8%), and Baidu (BIDU-6%) should be less affected.